The invention relates to a method and apparatus of inductively heating a refractory shaped member which has an internal space, e.g. a tubular internal space or a space forming a passage.
Such shaped members are in particular part of a melt discharge device or a melt dispensing device of a metallurgical vessel. They are preheated in order to prevent undesired cooling down of the melt flowing through them, particularly freezing thereof.
A refractory discharge for a continuous casting installation is disclosed in DE 38 42 690 A1, corresponding to U.S. Pat. No. 5,052,597. The discharge passage is surrounded from the exterior by an induction coil with which the outer wall within it may be inductively heated in a controlled manner. The coil is a component of the discharge unit. Such arrangement therefore is complex and expensive, which is of particular significance because such refractory shaped discharge members are wear members that must be replaced.
Refractory shaped discharge members, particularly immersed discharge members, are commonly heated by means of gas burners. This has the disadvantage that carbon, which is a material component of the shaped member, can burn out. It is also unfavorable that a non-uniform temperature distribution in the shaped member can occur during the heating process. Temperature differentials of, for instance, about 400 K have been observed. Furthermore, the heating process requires a considerable period of time.